The present invention relates to a method and apparatus for multiplexing in optical fiber communication. In a specific embodiment, the subject invention pertains to a multiplexer which couples multiple channels into an optical fiber, permits those channels to propagate a certain distance through the fiber, and finally processes the output of the fiber so to recover the individual input channels.
Typical multiplexing in optical fiber communication includes, for example, frequency-division multiplexing (FDM) and time-division multiplexing (TDM). Frequency-division multiplexing (FDM) uses frequency as the multiplexing domain. In FDM, signals generated by each sending device amplitude modulate different carrier frequencies. The modulated signals can then be combined into a single signal which can be transported by the link. After being outputted, FDM takes the combined signal, uses filters to decompose the multiplexed signal into its constituent component signals. Each component signal can then be passed to an amplitude demodulator, which can separate the carrier signal from the message signal. The message signal is then sent to an appropriate receiver. The carrier frequencies need to be different enough to allow the modulation and demodulation of the signals.
In TDB, multiple transmissions can occupy a single link by subdividing each transmission and interweaving the subdivided portions. TDM can be implemented in two ways: synchronous TDM and asynchronous TDM.
The subject invention relates to a method and apparatus for spatial domain multiplexing in optical fiber communications.